Monitoring Physical Downlink Control Channel for Small Data Transmission

1. A method performed by a user equipment (UE) for monitoring a physical downlink control channel (PDCCH), the method comprising: receiving, while in a radio resource control (RRC)_CONNECTED state, from a base station (BS), an RRC release message that includes a small data transmission (SDT) configuration; transitioning to an RRC_INACTIVE state from the RRC_CONNECTED state in response to receiving the RRC release message; initiating an SDT procedure based on the SDT configuration; determining whether an SDT search space set is received from the BS; monitoring the PDCCH by monitoring the SDT search space set during the SDT procedure when the SDT search space set is received from the BS; and when the SDT search space set is not received from the BS and the SDT procedure comprises a random access (RA)-based SDT procedure, monitoring the PDCCH by monitoring a common search space (CSS) set that is associated with an RA search space during the RA-based SDT procedure, wherein the SDT configuration comprises a configured grant (CG) configuration for SDT, a signaling radio bearer (SRB) configuration for SDT, and a data radio bearer (DRB) configuration for SDT.

2. The method of claim 1, wherein, when the SDT search space set comprises the CSS set, the CSS set is configured via a PDCCH common configuration (PDCCH-ConfigCommon) information element (IE).

3. The method of claim 1, wherein, when the SDT procedure comprises the RA-based SDT procedure, monitoring the PDCCH comprises monitoring the PDCCH after determining that an RA procedure is successfully completed and until the RA-based SDT procedure is terminated.

4. The method of claim 1, wherein, when the SDT procedure comprises the RA-based SDT procedure, monitoring the PDCCH comprises monitoring the PDCCH addressed to a cell-radio network temporary identifier (C-RNTI).

5. The method of claim 1, wherein, when the SDT procedure comprises a CG-based SDT procedure, the SDT search space set comprises a UE-specific search space (USS) set.

6. The method of claim 5, wherein, when the SDT search space set comprises the USS set, the USS set is configured via a PDCCH configuration (PDCCH-Config) information element (IE) received in the RRC release message.

7. The method of claim 1, wherein, when the SDT procedure comprises a CG-based SDT procedure, monitoring the PDCCH comprises monitoring the PDCCH after an initial transmission for the CG-based SDT procedure and until the CG-based SDT procedure is terminated.

8. The method of claim 1, wherein, when the SDT procedure comprises a CG-based SDT procedure, monitoring the PDCCH comprises monitoring the PDCCH addressed to a cell-radio network temporary identifier (C-RNTI) and a configured scheduling-radio network temporary identifier (CS-RNTI).

9. A user equipment (UE) for monitoring a physical downlink control channel (PDCCH), the UE comprising: at least one processor; and at least one non-transitory computer-readable medium coupled to the at least one processor and storing one or more computer-executable instructions that, when executed by the at least one processor, cause the UE to: receive, while in a radio resource control (RRC)_CONNECTED state, from a base station (BS), an RRC release message that includes a small data transmission (SDT) configuration; transition to an RRC_INACTIVE state from the RRC_CONNECTED state in response to receiving the RRC release message; initiate an SDT procedure based on the SDT configuration; determine whether an SDT search space set is received from the BS; monitor the PDCCH by monitoring the SDT search space set during the SDT procedure when the SDT search space set is received from the BS; and when the SDT search space set is not received from the BS and the SDT procedure comprises a random access (RA)-based SDT procedure, monitor the PDCCH by monitoring a common search space (CSS) set that is associated with an RA search space during the RA-based SDT procedure, wherein the SDT configuration comprises a configured grant (CG) configuration for SDT, a signaling radio bearer (SRB) configuration for SDT, and a data radio bearer (DRB) configuration for SDT.

10. The UE of claim 9, wherein, when the SDT search space set comprises the CSS set, the CSS set is configured via a PDCCH common configuration (PDCCH-ConfigCommon) information element (IE).

11. The UE of claim 9, wherein, when the SDT procedure comprises the RA-based SDT procedure, monitoring the PDCCH comprises monitoring the PDCCH after determining that an RA procedure is successfully completed and until the RA-based SDT procedure is terminated.

12. The UE of claim 9, wherein, when the SDT procedure comprises the RA-based SDT procedure, monitoring the PDCCH comprises monitoring the PDCCH addressed to a cell-radio network temporary identifier (C-RNTI).

13. The UE of claim 9, wherein, when the SDT procedure comprises a CG-based SDT procedure, the SDT search space set comprises a UE-specific search space (USS) set.

14. The UE of claim 13, wherein, when the SDT search space set comprises the USS set, the USS set is configured via a PDCCH configuration (PDCCH-Config) information element (IE) received in the RRC release message.

15. The UE of claim 9, wherein, when the SDT procedure comprises a CG-based SDT procedure, monitoring the PDCCH comprises monitoring the PDCCH after an initial transmission for the CG-based SDT procedure and until the CG-based SDT procedure is terminated.

16. The UE of claim 9, wherein, when the SDT procedure comprises a CG-based SDT procedure, monitoring the PDCCH comprises monitoring the PDCCH addressed to a cell-radio network temporary identifier (C-RNTI) and a configured scheduling-radio network temporary identifier (CS-RNTI).